1. Field of the Invention
This invention relates to a liquid crystal display (LCD), and more particularly to a liquid crystal display apparatus and method wherein pictures having an aspect ratio different from the liquid crystal panel""s normal aspect ratio can be displayed.
2. Description of Prior Art
Recently, there has been a general tendency to provide a picture with an aspect ratio of 16 to 9. This type of xe2x80x9cwide picturexe2x80x9d has a longer horizontal axis than the existing xe2x80x9cnormalxe2x80x9d picture having an aspect ratio of 4 to 3, thereby providing a more comfortable viewing area. In these wide screen LCDs, in order for the liquid crystal display to have the wide aspect ratio, its horizontal axis is made longer than conventional LCDs. However, it is desirable to have the xe2x80x9cwide picturexe2x80x9d LCDs capable of displaying a wide picture as well as a normal picture.
When the wide picture LCDs display a normal picture in the aspect ratio of 4 to 3 on the liquid crystal panel, it has to provide blanking i.e., a black display on the display region, shown by oblique lines in FIG. 1 on the left and right side thereof. In order to obtain this, conventional wide LCDs vary the frequency of a sampling clock for sampling the original picture data to thereby control the aspect ratio of the picture. However, this tends to produce a residual picture outside of the picture region in the aspect ratio of 4 to 3. Also, undesirable noise due to a horizontal synchronous signal pulse may be displayed on the left and right side region of the screen in the blanking area. Further, the conventional wide picture LCD apparatus has to combine the quasi-picture data to be displayed on the blanking display region with the original picture data and drive the liquid crystal panel with the combined picture data, in addition to the variation of the sampling clock of the picture data. This results in a complicated circuit configuration.
In an effort to overcome the above disadvantage in the conventional wide LCD apparatus, a liquid Crystal display device was disclosed in Japanese Patent laid-open publication No. Puyng 8-234698, published on Sep. 13, 1996 and filed by the Casio Co. Ltd. Here, when the wide liquid crystal display device displays the normal picture, it separately controls the sampling time of both the signal electrode drivers positioned in the liquid crystal panel on which the normal picture is to be displayed and the signal electrode drivers positioned in the liquid crystal panel on which the normal picture is not to be displayed. As a result, the liquid crystal display device could provide a blanking display on the left and right side area of the wide liquid crystal panel on which the normal picture was not displayed. However, in order to separately drive the signal electrode drivers, it is necessary to include separate picture data supply lines and concomitant circuitry. Due to this, the above liquid crystal display device has drawback in that its circuit configuration is complicated.
Accordingly, it is an object of the present invention to provide a liquid crystal display apparatus and method with a picture displaying function of different aspect ratio which can display on a liquid crystal panel a blanking picture without an inclusion of noise along with a picture an aspect ratio of which is different from that of the liquid crystal panel.
It is other object of the present invention to provide a liquid crystal display apparatus and method with a picture displaying function of different aspect ratio which can simplify a circuit configuration thereof.
In order to obtain the above objects, according to an aspect of the present invention, there is provided a liquid crystal display apparatus which comprises: (1) first signal electrode driving means for driving signal electrodes in a main region where the picture in a first or second aspect ratio is displayed; (2) second signal electrode driving means for driving signal electrodes in a peripheral region adjacent the main region where the picture in only one of the first and second aspect ratios, but not the picture in the other of the first and second aspect ratios, is displayed; and (3) timing control means for varying a picture data sampling start time of said first and second signal electrode driving means in accordance with the selected one of said first and second aspect ratios.
Furthermore, according to another aspect of the present invention, there is provided a method comprising the steps of: (1) driving first signal electrodes in a main region where the picture in a first or second aspect ratio is displayed; (2) driving second signal electrodes in a peripheral region adjacent the main region, where the picture in only one of the first and second aspect ratios but not the picture in the other of the first and second aspect ratios is displayed; and (3) varying a picture data sampling start time of said first and second signal electrodes in accordance with the selected one of the first and second aspect ratios.